Hithertobefore, the extruded noodles such as macaroni, spaghetti and other similar elongate pastas are usually produced by passing a noodle-forming raw dough through a extruder having die holes with exerting a high pressure on the dough and thereby extruding said dough into the noodle shape by means of the extruder, when the raw noodle strings or strands are to be formed from said dough. Owing to the extrusion under pressure, the inner texture of the extruded noodles so produced can show a much more highly tight state than that of the raw, rolled-and-cut noodles which are usually produced by rolling the noodle-forming raw dough into a dough web for use in the formation of noodle by means of a roller and then cutting the resulting noodle-forming dough web thinly into noodle strings or strands by means of cutting blade(s). When trying is done to pro cess the raw extruded noodle having the highly tight texture for a purpose that the extruded noodle would be imparted with the aforesaid instantly cookable property, this purpose usually cannot be achieved by merely processing the raw extruded noodle in the same way as in the known methods of processing the raw, rolled-and-cut noodles to make these noodles instantly cookable, by which methods the raw, rolled-and-cut noodle can successfully be imparted with the desired instantly cookable property. Thus, even if the raw extruded noodle is simply subjected to the known methods for processing the raw, rolled-and-cut noodles instantly cookablely, there can occur such problems that the extruded noodle having been so processed by the above-mentioned known methods of processing the rolled-and-cut noodles instantly cookably is not capable of being restored to the soft, cooked and favorably edible state in a short time upon simply pouring a volume of hot water onto and over the so processed noodles and keeping them in the resultant hot water pool, and that the extruded noodle having been processed by the known methods of processing the rolled-and-cut noodles instantly cookably cannot give a good chewiness to consumers after it has been restored to the edible state by immersing it in the pool of poured hot water for a while. For instance, there has been reported such a method for producing an oil-fried noodle capable of being cooked instantly, which comprises admixing potato starch and edible oil with wheat flour in a proportion of 15-70% by weight of the potato starch based on the weight of wheat flour and in a proportion of 1-4% by weight of the edible oil based on the weight of wheat flour, kneading the resultant starting flour mixture together with water added thereto, rolling the resulting kneaded dough material into the shape of a noodle-forming dough web by means of roller, cutting the rolled dough web by cutting balde(s) to form noodle strings or strands, steaming the noodle strings or strands in a steamer, then treating the steamed noodle strings so as to absorb water therein in order to increase the water content of the noodle strings to a water content of 40-50% by weight, and frying in oil the noodle strings having absorbed water. This method is said to provide such a noodle product which can give a chewiness similar to that of the rolled-and-cut noodles which have been cooked in a usual way without having been fried in oil (see Japanese patent No. 1,110,720 published under Japanese patent publication "Kokoku" No. 36896/81).
Nonetheless, when the method of the Japanese patent No. 1,110,720 is simply applied to for the production of the extruded and elongate pasta such as spaghetti and the like, the noodle product so produced by said method can exhibit such drawbacks that the resultant noodle product is not restorable to a favorably edible state in a short time upon simply pouring a volume of hot water to the noodle and keeping the noodle immersed in the resultant hot water pool, and that the noodle so treated by immersion in the pool of the poured hot water shows a chewiness which is not elastic.
In these circumstances, various methods were proposed in the past for the production of the extruded noodles having the instantly and favorably cookable property. For instance, there has been proposed such a method for preparing macaroni capable of being cooked instantly and giving good chewiness, which comprises providing a non-kneaded mixture of wheat flour with water containing wheat flour as main component and having a water content of 25-35% based on the weight of said mixture, granulating said non-kneaded mixture of wheat flour with water into the form of granules, preliminarily steaming the resultant granules with the granules being placed on and dispersed over a flat plate, extruding the so steamed granular material into the form of macaroni by passage through an extruder, then applying optionally water onto the surfaces of the noodle strings as formed, subsequently steaming the noodle strings in a steamer, and finally drying the steamed noodle strings (see Japanese patent No. 1,097,491 published under Japanese patent publication "Kokoku" No. 39614/81). However, the instant pasta product as produced by the method of Japanese patent No. 1,097,491 is actually not capable of being restored to a soft and favorably edible state in a short time when a volume of hot water is poured to the pasta with subsequently keeping it immersed in the hot water pool. Besides, this pasta product yet cannot give an elastic chewiness essentially characteristic to the usual pastas to a satisfactory extent.
Taking into account the above actual situation of the prior art methods, we, the present inventors, have made various studies in an attempt to provide such an extruded noodle capable of being cooked instantly which is readily restorable to a favorably edible state in a short time only by simply pouring a volume of hot water to the noodle placed in a vessel and keeping the noodle in the resultant hot water pool, and which can give the elastic chewiness or palatability characteristic to the usual, extruded elongate pastas or noodles. As a result, we have now found that an instantly cookable, extruded noodle product having the desired excellent properties can be obtained when the extruded noodle is produced by a new process which comprises steps of providing and using a noodle-forming raw dough material containing a proportion of raw tapioca starch, extruding this dough material into noodle strings or strands, with forming one groove or several grooves which extends or extend longitudinally in the noodle strings as extruded, steaming the raw noodle strings having the groove(s) in a steamer, then treating the steamed noodle strings so as to absorb water therein and thereby to increase the water content of the noodle to a predetermined degree, and subsequently frying the noodle strings with the increased water content in oil. Further, we have found that if any one of the steps and the operating requirements as stipulated in the present inventors' new process is omitted, it is disadvantageously likely to invoke that the surfaces of the noodle strings would readily blister during the oil-frying step of the process, that the noodle during the immersion in the pool of the poured hot water would be difficult to be restored to the soft and favorably edible state, and that the noodle, even after being restored to the edible state, would exhibit chewiness or palatability which is not elastic. On the basis of these findings, we have accomplished this invention.